Yeast expiry dates do matter!

[nakros]

For what it's worth,

I bottled an amber ale almost 3 weeks ago. It spent 2 weeks in primary and 2 weeks in secondary.

The yeast packet (Muntons) had a stamp of early 2006, and I wondered at the time if it would make much of a difference (I've read that 2 years is pushing it for dry yeast).

The beer originally fermented out properly, if a bit delayed (didn't start making krausen until around 3 days after I pitched - SG 1.048 FG 1.008), so I figured it would be fine. Well, after the 2 weeks in secondary, I had less than 1/16" of trub -- it was literally just a dusting at the bottom of the carboy.

I cracked a few tonight, and they are essentially flat. A slight carbonation (if I pour really hard, I get a bit of a head). I am guessing the yeast are just too tired to continue. At least it tastes good!

Fermented, cleared, and bottle conditioned at a constant 68F for the entire time. As far as I can see, the only variable is the age of the yeast.

Just sharing my experience -- If your yeast packet is over 2 years old, don't bother -- buy another. I certainly won't dump it as it is drinkable, but I definitely will make sure I use only fresh yeast from now on.

 

[farmbrewernw]

if the yeast was capable of fermenting than you have enough active yeast to bottle carb just let them sit longer they will become fizzy over time.

 

[homebrewer_99]

I used a vial of liquid yeast that was date Nov 06 on my last batch of Weizen....no problems...

 

[karbinator]

I agree with Farm brew....

An expert I am not.
I had, and still have several vials of WLP's that are 2008.
The guys here said it would be fine IF
I made a starter. This is the only way to insure out of date stuff.
Really. Fr the dry yeast that's old, at least hydrate it prior to pitching.

 

[Cookiebaggs]

I just used a mason jar of washed kölsch yeast that was over 10 months old. It took 1 day longer than normal to take off on the stirplate but it fermented my beer very fast and clean and violent.

 

[Revvy]

How long have you waited to check on your carbonation...if it's under 3 weeks AND it's being stored at less that 70 degrees, THAT's why your beer isn't carbed...NOT because your yeast suddenly can't eat a few ounces of sugar...and if it's been 3 weeks, then it may STILL need a few more weeks, I've had some beers not "pop" for up to 8 weeks...

If it fermented your beer originally, then it also reproduced new yeasties from the viable yeast cells (that's why we can grow a huge 1/2 gallon starter from the dregs at the bottom of a bottle of beer...because the surviving cells reproduce...

That's not the reason your bottles aren't carbed yet...

Post Hoc Ergo Propter Hoc... (look it up)

 

[Homercidal]

Yes, although I agree that on principle you should buy yeast before the expiry date, if your yeast fermented your beer, then it will prime your bottles. However, there could be another reason for it not carbing. Could be needs more time at 70 degrees. Who knows. The fact is that if your fermenting was good, then you have good yeast.

 

[Cookiebaggs]

I generally crash cool the secondary to clear the beer for a week or so and there is still enough yeast in suspension to bottle condition with no problems.

As was said, give it a little more time. Preferably at 70 degrees.

 

[nakros]

Hmm... I think I may have to apologize to those yeast tonight. I have been calling them lazy little jerks for quitting before the job was finished.

Thanks for the answers!